Such locking mechanisms are being used in freight loading systems as so-called YZ-latches and serve to fix or lock cargo pieces such as containers or pallettes in the lateral and vertical direction of their stowed position. For this purpose the latches reach over appropriate projections on the cargo pieces. A frequent requirement for such locking mechanisms which extend out above the loading floor is, that the mechanisms can be rolled over when the freight is transported in one direction, and that the latches hold and lock the cargo pieces in another direction.
German Patent Publication (DE-PS) 3,222,202, corresponding to U.S. Pat. No. 4,583,896 (Vogg et al.) discloses a locking mechanism as described above. The known mechanism is pushed below the plane of the loading floor when a piece of freight rolls over the mechanism from a direction opposite to the direction in which the latch claw faces. The latch claw is returned to its initial position by the power of a tension spring after the roll over, and in the other direction locks the cargo pieces or respectively requires an unlocking action.
In connection with the YZ-latches mentioned above, which act on the sides of the cargo pieces, the various widths of the freight pieces create a problem. In different sections of the hold there are frequently loaded containers or pallettes with a width of 125 inches as well as some with a width of only 62 inches. The latter are placed next to each other in the space provided for 125 inch wide pieces, so that only a lateral space of one inch remains between the pieces.
U.S. Pat. No. 3,927,622 (Voigt) describes a freight lashing apparatus, especially for aircraft, in which freight movement sensing bails are responsive to freight movements forward, and in both lateral directions for retracting the locking mechanism. Additionally, an unlocking device is responsive to freight movements in a direction reverse to the forward direction. Thus, the known mechanism can be retracted into a recess below the loading floor level in response to forward, backward and lateral right and left freight movements. The latches are arrested in the working position. The latch claw is effective in but one direction for locking or arresting a cargo piece in a stowed position.